The determination of the thermal conductivity of solid materials is of interest for selecting materials to be used in construction and manufacturing, for example in, processing machinery, and fabrication processes. Of particular interest is the determination of thermal conductivity, generally denoted K, by the use of a heat flow device called a Differential Scanning Calorimeter (DSC). One commercially available type of DSC is supplied by E.I. DuPont de Nemours and Co. under their Model No. 990. Generally speaking, this device utilizes a cylindrical sample of the solid material for test which is placed in a small pan and subjected to a controlled pattern of heat applications while thermocouples record temperatures associated with the sample. One detailed method of analyzing the sample is disclosed in a paper by Jen Chiu and P. G. Fair entitled "Determination of Thermal Conductivity by Differential Scanning Calorimetry", Thermochimica Acta 34 (1979) 267-273. The DSC partially performs the solid state thermal conductivity calculations through the use of a Fourier equation for heat flow (See equation 1). ##EQU1## where; K represents the thermal conductivity, Q is the heat flow, T.sub.2 is the temperature of the face of a cylinder of material under test that is heated (i.e., "hot face") and T.sub.1 is the temperature of the "cold face", L is the length of the cylinder, and "A" is the cross-sectional area of the cylinder.
The thermal conductivity, K, measurement is made on the cylindrical sample with Q, T.sub.2 and T.sub.1, stable and the system in "thermal equilibrium". At this point the thermal gradient is firmly established in the material and is not changing.
The advantages of using a DSC approach for K measurement over other heat flow approaches are: 1) the simultaneous acquisition of specific heat data and K data, 2) the option of measuring K while heating the sample at a selected rate, 3) the use of small samples in the DSC, and 4) the short time needed for analysis.
All of the DSC approaches to the measurement of thermal conductivity described in the literature have definite advantages over dedicated thermal conductivity instrumentation but, compromise the utility and strengths of the DSC. The present inventive method of measuring the thermal conductivity value using a DSC as described herein takes full advantage of all that the DSC has to offer to provide K data in a dynamic range (selected rate of change of T.sub.2).